Method of pickling sheets or the like



Oct. 14, 1941. ss 2,259,277

METHOD OF PICKLING SHEETS OR THE LIKE Filed Nov. 28, 1938 z i I Patented Oct. 14, 1941 2,259,277 METHOD OF PICKLINI? SHEETS OR THE LIK Harry W. Theiss, Louisville, Ohio, assignor to Continental Steel Corporation, Kokomo, Ind.,

a corporation of Indiana Application November 28, 1938, Serial No. 242,757

1 Claim.

The method of thepresent invention is directed primarily to improvements in the art of pickling metal sheets as a preliminary step to the subsequent coating of the sheets by electrolytic or similar process, although the manner in which the sheets are directed through the bath is not necessarily confined to a pickling operation, since a bath of some other character may be employed. However, the present invention possesses especial and peculiar advantages in the pickling of metal sheets, so that special reference will be made to such an operation as the one for which the feeding method of the present invention is more particularly designed.

The essential or outstanding feature of the present method resides in the feeding of separate metal sheets of a relatively flexible character in processional relation to one another and through an undulatory path of travel through the bath, which path is one which causes each sheet to be alternately immersed in the bath and elevated therefrom during the progress of the sheet from end to end of the bath.

The present invention also is directed to the means provided for applying the necessary feeding force to the individual sheets at points elevated above the level of the liquid, so that eachof the sheets will be fed forward during the periods of its emergence from the liquid, which greatly simplifies the feeding operation, in that it locates the feeding mechanisms at points where convenient access may be had thereto and at the same time maintains constant progression of a procession of sheets in uninterrupted series from end to end-of the bath.

By affording an undulatory path of travel to the individual sheets, marked advantages are attained in speeding up the pickling operation and in securing uniformity in the pickling action throughout the entire exposed surface on both sides of each sheet, which results in a better appearance of the finished sheets and in less rejections and in a definitely improved quality, which improvements are reflected in the sheets which are subsequently coated with various protective or decorative finishes.

The method of the present invention possesses numerous other special advantages which will be referred to more in detail after a full description has been set forth. I

In the drawing, which illustrates a convenient form of apparatus for carrying forward the steps comprised in the present method- Figure 1 is a diagrammatic view of a pickling bath showing the means provided for feeding individual sheets from end to end thereof in an undulatory path of travel; and

Fig. 2 is an enlarged view showing in fuller detail the arrangement of the feed rollers for the sheets and the guides for maintaining the undulatory path of travel.

In carrying out the method of the present invention, a stack of sheets I0 is maintained at one end of an elongated tank H containing therein an acid pickling bath l2 provided for the removal from the surfaces of the sheets of particles of metal or scale adhering thereto. The sheets are elevated individually by suction cups l3, or other appropriate lifting means, until they come into contact with magnetic feed rolls I4 which advance each sheet in turn into the bite of the first pair of aseries of feed rolls I5 which are located in spaced relation from end to end of the tank and above the surface of the liquid therein contained.

The first set of feed rolls I5 is located adjacent to the entering end of an undulatory guideway l6 extending from end to end of the tank and configured to alternately submerge the sheets below the surface of the liquid and alternately elevate them above said surface. The guideway as a whole is'comprised of a series of upper slats I1 and a series of lower slats l8, the respective slats of each series being spaced laterally from one another so as not to impede the inflow of liquid into the space intermediate the upper and lower slats which affords the path of travel for the sheets.

As shown, the guideway as a whole is divided into sections between the adjacent pairs of feed rolls l5, and each section has the slats so disposed that at the mouth or entering end IQ of the section the vertical spacing of the upper and lower slats is greater than at the discharging end 20 of the section, which arrangement affords a throated entrance adjacent to ach set of rollers for facilitating the entry of the sheets into the guide section.

The arrangement is one which permits the required number of sections and associated rollers to be employed to accommodate a pickling tank of the desired length, and as shown all of the rollers are driven in unison from a common source of power which is preferably an electric motor 2| which drives through a reducing gear in a case 22 to a sprocket wheel 23, which constitutes the universal driving element. The sprocket wheel 23 drives through sprocket chains 24-24, each of which is carried around a transmission sprocket wheel 25 which is directly connected with one of the center feed rollers of the series, while the remaining feed rollers are driven in unison by a sprocket chain 26, so that all of the lower rollers in the feeding series will be positively driven in the same direction and at a uniform speed.

As shown, the upper rollers of each feeding pair are backed by springs 51, so that a firm though yielding contact is maintained between the rollers. If desired, heat may be imparted to the liquid in the bath by means of submerged gas heaters 28, or other appropriate heating means, each heater being preferably located in position td surround the lower turn or bend of one of the sections of the guideway.

The length of each section of the guideway and the spacing of the feed rollers is determined with reference to the intended length of the sheets and is so computed that before the trailing edge of a given sheet progresses beyond the bite of. a given pair of feed rollers, its leading edge will enter the bite of the next adjacent pair of feed rollers, so that continuity in feedin speed of the individual sheets will be maintained throughout, and this irrespective of I whether or not gaps occur in the procession of sheets passing through the bath.

In order tospeed the operation to the utmost, it is desirable for the sheets to follow one another without gaps] or interruptions so,

that the leading edge of each sheet in the procession will lie immediately adjacent to the trailing edge of the preceding sheet, and in order to maintain this sequence it is desirable to actuate the-vacuum lifting cups and the magnetic rollers in properly timed relation to the speed of adsheet during its progress will be constantly sub-- iect to flexation first in one direction and then in the other during its period of progression, which mode of travel serves not only to cause a more intimate impingement of the liquid against the upper and lower surfaces of the sheet, with a resulting agitation and scouring action, but also serves, through the constant bending or flexation of the sheet itself, to loosen up scale or surface particles and to afford more ready access of the acid to the surface of the sheet. 1

By thus subjecting the sheets constantly to varying fiexation, and by recurrently reve'rsing the direction of flexation and alternately submerging and elevating the sheets into and out of the liquid of the bath, a more rapid, uniform and effective action is obtained than would be possible in the feeding of sheets in an undeviating plane and in. edgewise relation from end to end of the bath, so that the quality and uniformity of the sheets is materially improved and the operation greatly accelerated as compared with methods commonly in use at the present time.

Furthermore, it has been found that by alternately submerging and exposing the sheets, the pickling rate is practically doubled as compared with a continuous method in which the sheets are constantly submerged during the entire pickling operation. It is also to be noted that all moving mechanism of the unit is located above or outside of the liquid at points where it is readily accessible, so that changes or readjustments can be speedily made without draining the tank, which is a definite advantage in the servicing of the equipment and in prolonging the life of the moving parts. It is, also to be noted that the undulatory character of the path of travel results in economy of space and in a longer path of movement within given linear dimensions than would be otherwise possible.

It has also been found that the iron loss is reduced as compared with the present method of pickling, by reason of the fact that a more uniform and better controlled operation is afforded, so that over-pickling, resulting in excessive iron loss, is eliminated, with a consequent saving in acid as well as in an' improvement in the character and quality of the product.

It has also been found that the volume of solution required is much less than in the methods commonly in use at the present time, which results in a saving of acid and water, since a pickling solution can be used only for a limited period of time before the iron salts are built up to a prohibitive degree, which requires the solution to be discarded, so that with a less quantity of solution and a reduction in theiron loss, a

' less volume of acid and water will be wasted.

, duced, due to a more effective action of the pickling liquid upon the surface, which speeds up the rate and uniformity of the action with a resultant decrease in the tendency to blister.

The method of feeding the sheets individually permits sheets of any length or width within convenient limits to be handled, since there is no need ofwelding or stitching the sheets together, which has been the common practice in previous methods of continuous pickling and which necestent without difliculty.

Although the above advantages indicate that the method of handling the sheets possesses peculiar and distinct advantages in the performance of a pickling operation, it will be understood that the method of undulatory feeding is one which may be applied to sheets transported through a bath intended for some other purpose, so that it will be understood that unless indicated in the claim it is not the intention to limit the feeding to a pickling operation.

I claim:

The method of feeding sheets through a picklingbath which consists in providing an undulatory pathway for the sheets from end to "end of the bath, which pathway recurrently extends below and recurrently emerges above the surface of the liquid and imparting to the sheets a feeding force to compel the sheets to move through said pathway and cause the sheets to be bent back and forth with sufficient frequency and abruptness and to a sufiicient extent to dislodge scale and other impurities adhering to the surfaces of the sheets whereby the sheets are mechanically cleaned of such scale and other impurities simultaneously with the'pickingof the sheets.

HARRY W. THEISS. 

